1. Field of the Invention
The present invention relates to an absorbent article for absorbing body fluids and exudates, such as urine. More particularly, the present invention relates to absorbent garments, such as disposable diapers and adult incontinence garments, which are configured to absorb body exudates while also helping to provide reduced skin hydration.
2. Description of the Related Art
Many known diaper configurations employ absorbent materials located between a liquid pervious topsheet and a vapor and liquid impermeable backsheet. Such backsheets are well suited to prevent the migration of liquid waste from the absorbent materials to the outer garments of a wearer. Unfortunately, the use of liquid and vapor impermeable backsheets can result in a relatively high degree of humidity within the diaper when in use. This may result in relatively high skin hydration levels and may lead to the onset of diaper rash.
In order to reduce the humidity level within diapers, breathable polymer films have been employed as outer covers for absorbent garments, such as disposable diapers. The breathable films are typically constructed with micropores to provide desired levels of liquid impermeability and vapor permeability. Other disposable diaper designs have been arranged to provide some level of breathability at the leg cuff regions of the diaper. Still other disposable diaper designs have been arranged to provide humidity transfer regions in the form of breathable panels in otherwise vapor-impermeable backsheets or to employ perforated regions to help ventilate the garment.
Conventional absorbent articles, such as those described above, have not been completely satisfactory. For example, articles which employ a microporous outer cover can exhibit a cold and clammy feeling when the garment is wetted and moisture is evaporating through the microporous film. The articles which employ perforated films or breathable panels can exhibit excessive leakage of liquids from the article and can excessively soil the wearer""s outer garments. In addition, when the absorbent material of the article becomes loaded with liquid, the wet absorbent can block the escape of moisture from the wearer""s skin. Such absorbent garment designs have not been able to sufficiently reduce the hydration of the wearer""s skin. As a result, the wearer""s skin has remained susceptible to rashes, abrasion and irritation.
In response to the difficulties and problems discussed above, a new disposable absorbent article which has a breathability gradient has been discovered.
As used herein, reference to xe2x80x9chumidity transferxe2x80x9d refers to the transfer of water vapor from the interior of a diaper, when in use on a wearer, to the exterior of the diaper (ambient atmosphere).
As used herein, a substantially liquid impermeable material is constructed to provide a hydrohead of at least about 60 cm (centimeters), desirably at least about 80 cm, and more desirably at least about 100 cm. A suitable technique for determining the hydrohead value is the Hydrostatic Pressure Test which is described in further detail herein below.
As used herein, a substantially vapor permeable material is constructed to provide a water vapor transmission rate (WVTR) of at least about 100 g/sq.m/24 hr, desirably at least about 250 g/sq.m/24 hr, and more desirably at least about 500 g/sq.m/24 hr. A suitable technique for determining the WVTR value is the WVTR Test which is described in further detail herein below.
In one aspect, the present invention relates to an absorbent article which defines a garment facing surface, a body facing surface, a front waistband section, a rear waistband section and an intermediate section which interconnects the front and rear waistband sections. The absorbent article comprises a first zone of vapor permeability which is located on the garment facing surface and which defines a water vapor transmission rate of from about 100 to about 2500 g/sq.m/24 hr. The absorbent article further comprises a second zone of vapor permeability which is located on the garment facing surface and which defines a water vapor transmission rate of at least about 3000 g/sq.m/24 hr. The first zone of vapor permeability may define an area which is at least about 75 percent of the garment facing surface of the absorbent article. The first zone of vapor permeability may further define a width which is less than a width of the absorbent article and the second zone of vapor permeability may extend beyond the first zone of vapor permeability thereby providing a breathability gradient across the width of the absorbent article.
In another aspect, the present invention relates to an absorbent article which comprises a vapor permeable backsheet which includes a first zone of vapor permeability which defines a water vapor transmission rate of at least about 100 g/sq.m/24 hr and a second zone of vapor permeability which defines a water vapor transmission rate of at least about 3000 g/sq.m/24 hr. The absorbent article further comprises a liquid permeable topsheet which is positioned in facing relation with the backsheet and an absorbent body located between the backsheet and the topsheet. In a particular aspect, the first zone of vapor permeability covers at least about 75 percent of a garment side of the absorbent body.
In still another aspect, the present invention relates to an absorbent article which comprises a substantially liquid impermeable, vapor permeable backsheet which defines a water vapor transmission rate of at least about 1500 g/sq.m/24 hr, a liquid permeable topsheet which is positioned in facing relation with the backsheet, and an absorbent body which is located between the backsheet and the topsheet. The absorbent article further comprises a vapor permeable barrier layer which is smaller in size than the backsheet and which is located between the absorbent body and the backsheet. The combination of the vapor permeable barrier layer and the vapor permeable backsheet defines a water vapor transmission rate of from about 100 to about 2500 g/sq.m/24 hr. In a particular aspect, the substantially liquid impermeable, vapor permeable backsheet is constructed to provide a hydrohead of at least 60 cm. The vapor permeable barrier layer may define a water vapor transmission rate of from about 100 to about 5000 g/sq.m/24 hr.
The present invention advantageously provides an improved absorbent article which substantially reduces the hydration of the wearer""s skin when compared to conventional absorbent articles. Thus, wearer""s of absorbent articles made according to the present invention should have a reduced incidence of skin irritation or rash.